1. Field of the Invention
The invention relates to apparatus for implanting devices in atrial appendages. The devices may be used to filter or otherwise modify blood flow between the atrial appendage and an associated atrium of the heart to prevent thrombi from escaping from the atrial appendage into the body's blood circulation system. In particular the invention relates to apparatus for percutaneous delivery and implantation of such devices.
2. Description of the Related Art
There are a number of heart diseases (e.g., coronary artery disease, mitral valve disease) that have various adverse effects on a patient's heart. An adverse effect of certain cardiac diseases, such as mitral valve disease, is atrial (or auricular) fibrillation. Atrial fibrillation leads to depressed cardiac output. A high incidence of thromboembolic (i.e., blood clot particulate) phenomena is associated with atrial fibrillation, and the left atrial appendage (LAA) is frequently the source of the emboli (particulates).
Thrombi (i.e., blood clots) formation in the LAA may be due to stasis within the fibrillating and inadequately emptying LAA. Blood pooling in the atrial appendage is conducive to the formation of blood clots. Blood clots may accumulate and build upon themselves. Small or large fragments of the blood clots may break off and propagate out from the atrial appendage into the atrium. The blood clot fragments can then enter the body's blood circulation and embolize distally into the blood stream.
Serious medical problems result from the migration of blood clot fragments from the atrial appendage into the body's blood stream. Blood from the left atrium and ventricle circulates to the heart muscle, the brain, and other body organs, supplying them with necessary oxygen and other nutrients. Emboli generated by blood clots formed in the left atrial appendage may block the arteries through which blood flows to a body organ. The blockage deprives the organ tissues of their normal blood flow and oxygen supply (ischemia), and depending on the body organ involved leads to ischemic events such as heart attacks (heart muscle ischemia) and strokes (brain tissue ischemia).
It is therefore important to treat cardiac conditions to prevent fragments or emboli generated by any blood clots that may have formed in the atrial appendages, from propagating through the blood stream to the heart muscle, brain or other body organs.
Some recently proposed methods of treatment are directed toward implanting a plug-type device in an atrial appendage to occlude the flow of blood therefrom.
A preventive treatment method for avoiding thromboembolic events (e.g., heart attacks, strokes, and other ischemic events) involves filtering out harmful emboli from the blood flowing out of atrial appendages. Co-pending and co-owned U.S. patent application Ser. No. 09/428,008, now U.S. Pat. No. 6,551,303; U.S. patent application Ser. No. 09/614,091, now U.S. Pat. No. 6,689,150; U.S. patent application Ser. No. 09/642,291, now U.S. Pat. No. 6,652,555; U.S. patent application Ser. No. 09/697,628, and now U.S. Pat. No. 6,652,556; and U.S. patent application Ser. No. 09/932,512, now published as U.S. Application Publication No. 20020022860A1, all of which are hereby incorporated by reference in their entireties herein, describe expandable filtering devices which may be implanted in an atrial appendage to filter the blood flow therefrom.
The implant devices in a compact state may be delivered to their atrial appendage situs percutaneously through femoral or jugular blood vessels using conventional catheterization apparatus. The position of an implanted device may be observed using common imaging techniques, for example, radiography or echocardiography. The implant devices are deployed by expanding them in situ. The devices are retained in position by expandable structures which engage surrounding atrial appendage tissue. The expandable structures may include tissue piercing anchors.
To function effectively the devices must be deployed from suitable positions within or about the atrial appendages. For example, the filter elements of a device must be correctly centered or positioned across an atrial appendage ostium for the device to properly intercept and filter blood flowing out of the atrial appendage. Placing a device in a suitable deployment position may require position probing or adjustment from an initial as-delivered position.
It would therefore be desirable to provide catheterization apparatus having positioning guides, which enable controlled position probing and readjustment of the initial as-delivered implant device position to place the device in a suitable deployment position in the atrial appendage.
Further, the implant procedures may include transseptal catheterization which involves puncturing an atrial septum and advancing an access sheath through the septum. The access sheath provides a conduit through which an implant device may be delivered across the septum into the adjoining atrium. Inadvertent movement of the sheath during the catheterization procedure may lead to undesirable medical complications. For example, retrograde slippage may cause the sheath to disengage from the septum, which in turn may necessitate repeated puncturing or crossing of the septum to regain access to the adjoining atrium. Further, instability in the position or orientation of the access sheath may make the delivery of a device for placement in an appendage geometrically difficult.
It would therefore also be desirable to provide transseptal catheterization apparatuses which include securement devices for restraining the movement of and securing the position of the access sheath traversing the septum.